Method of inflating elastomeric chambers with nitrogen gas



Sept. 23, 1969 L. R. SPERBERG 3,468,348

METHOD OF INFLATING ELASTOMERIC CHAMBERS WITH NITROGEN GAS Filed Jan. 9, 1967 I N VIz'NTOR. LAWRENCE R. SPERBERG s4 BY 66 I v MARCUS L. BATES United States Patent 3,468,348 METHOD OF INFLATING ELASTOMERIC CHAMBERS WIIH NITROGEN GAS Lawrence R. Sperherg, Box 12308, El Paso, Tex.

Filed Jan. 9, 1967, Ser. No. 608,173 Int. Cl. B6511 31/04; F17d 1/04; F17c 7/02 US. Cl. 141-1 13 Claims ABSTRACT OF THE DISCLOSURE Cross reference to related applications: Serial No. 601,275, filed November 21, 1966.

BACKGROUND OF THE INVENTION When an elastomeric chamber, such as a tire, is inflated with an inert gas, as exemplified by nitrogen, the durability is greatly increased as compared to a tire having oxygen contained in the inflating agent, as exemplified by air. Helium, carbon dioxide, carbon monoxide, nitrogen, and the rate gases are suitable inert gaseous inflating agents. Nitrogen is one of the more desirable inert inflating agents since it is commercially available in either high pressure cylinders, or in liquid form.

Liquid nitrogen has a critical pressure of about 500 psi. at its critical temperature of l47 C. When liquid nitrogen is placed within an insulated closed vessel, and provided with valve means by which the vapor pressure of the gas phase contained within the vessel is maintained within a predetermined limit, the rate of evaporation of the liquid nitrogen may be greatly retarded.

SUMMARY Pressurized gaseous nitrogen is substituted for the air compressor in the conventional tire inflation system'to thereby enable pneumatic elast-omeric gas chambers, such as pneumatic tires, for example, to be inflated with an inert gas.

One method of the present invention utilizes a system that includes high pressure gas cylinders that are attached to a storage tank by means of a manifold that includes a flow control valve.

The present invention also contemplates a method of utilizing liquid nitrogen by the provision of suitable valve means for regulating the evaporation rate of the liquid nitrogen, as well as maintaining a predetermined pressure within the inflation system including the storage tank.

Another form of the invention utilizes a low pressure system wherein liquid nitrogen contained in an insulated vessel is directly connected to a storage tank, with the storage tank including an automatic valve for controlling the pressure therein.

ln'each of the above embodiments, the pressurized inert gas system finds utility apart from the inflation of elastomeric gas chambers, as for example, the provision of a source of fluid power required to power air driven tools, and the like.

Accordingly, one object of this invention is to provide a method of inflating tires with an inert gas by using either high pressure bottled nitrogen or liquid nitrogen as the supply of inert gas.

Another object of this invention is the provision of a ice method of using liquid nitrogen for inflating pneumatic tires. 1

Still another object of this invention is to provide a method of controlling the flow of gaseous nitrogen from a vessel containing liquid nitrogen in a manner that re duces the requirements for the venting of nitrogen to a minimum.

The apparatus illustrated and disclosed herein, through which the above method of this invention is carried out, provides a new apparatus which also constitutes a step forward in the art of gas distribution. Therefore, the objects of this invention include the specific examples of each of these apparatus as set forth herein.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a partly diagrammatical and partly schematical representation of the apparatus that provides a means for carrying the method of the present invention into practice;

FIGURE 2 is a partly diagrammatical, partly schematical representation of another means by which the method of the present invention may be carried into practice.

DESCRIPTION OF THE PREFERRED EMBODIMENT Looking to the details of FIGURE 1, there is seen illustrated therein a pair of high pressure cylinders, 10 and 12, each containing gaseous nitrogen and having an outlet 14 and 14', each of which are suitably tied together and to the manifold or flow line 16. The manifold includes a valve 18 that connects the flow line 16 to the flow line 20. Manually actuated valve 22 is located in flow line 20 and connects the manifold to a storage tank 24. The valve 18 includes a motor section 26 which controls the rate of flow through valve 18 in accordance with a predetermined pressure at flow line 28. The valve 18 and motor 26 may be a common diaphragm actuated motor valve that positions valve 18 in accordance with the pressure sensed at flow line 28. A drain valve 30 is suit-- ably disposed at the lower extremity of the storage tank. At the upper extremity of the storage tank there is provided a manually actuated valve 32 through which nitrogen gas may flow to inflating conduit 34 to thereby provide a source of pressurized nitrogen for inflating pneumatic tires. The storage tank 24 and flow line 34 are preferably the existing storage tank and tire inflation apparatus such as commonly found in gasoline filling stations and garages.

Looking now to the details of FIGURE 2, wherein there is disclosed an insulated high pressure liquid nitrogen container or vessel 40 that has any desired capacity; from five to one thousands gallons, for example; and includes a fitting 42 that is removably aflixed by a valve 81 to a flow line 44. Flow line 44 provides a source of pressurized gaseous nitrogen to either of two different manifolds. The first manifold includes flow lines 46 and 48 that in turn are connected through the illustrated valve arrangement to where they join at flow line 47 which includes valve 82 which is connected to the flow line 50. Valves 52 and 54 are connected in parallel between flow lines 44 and 47. Valve 52 includes a motor 56 that actuates valve 52 in accordance with the pressure sensed by the pilot at downstream conduit 58. Valve 54 includes a motor 60 that is actuated in accordance with the pressure sensed by the pilot at upstream conduit 62.

The second manifold provides a direct connection from the vessel 40 to the storage tank 64 and includes flow line 44, 48, 49, valve 84, and flow line 50. The second manifold provides a low pressure system, and accordingly, requires a vessel 40 of much lower strength as compared to the first manifold.

Valve 66 provides a drain at the lower extremity of the storage tank. At the upper extremity of the storage tank there is located a valve 68 Within the inflating flow line 70. The flow line 70 provides a pressurized source of nitrogen gas to a conventional inflating means, such as a flexible hose and an air chuck, that is generally found in filling stations or garages.

The upstanding nipple 72 is connected to a valve 74 that controls the flow of nitrogen gas through conduit 76 to the atmosphere, as indicated. Valve 74 is actuated in accordance with the position of motor 78 that in turn includes a pilot that actuates valve 74 in accordance with the pressure sensed at conduit 80.

It should now be evident to those skilled in the art that the liquid nitrogen vessel 40 may be connected to the storage tank 64 by either the first or second manifold arrangement described above, by proper selection of the position of valves 82 and S4, or by the proper selection of manifolds employed.

Operation In the operation of the device of FIGURE 1, a multiplicity of high pressure gas cylinders, and 12, each containing gaseous nitrogen, are connected together in parallel by the illustrated conduits or flow lines that form the manifold which provides a flow of high pressure nitrogen gas to the storage tank 24. The illustrated valves 35 and 35 are conventional valves that are generally attached to high pressure cylinders. Motor 26 is a diaphragm actuated type motor having a pilot that receives a source of actuating pressure from the flow line 20. The pilot 0* motor 26 is adjusted to actuate the valve '18 to thereby maintain the pressure in the tank 24 within a predetermined maximum and minimum pressure limits, as for example, between 100 and 140 p.s.i. Valve 22 is provided in the flow line so as to enable the upstream side of the system to be disconnected, thereby avoiding the necessity of bleeding the nitrogen gas from the tank 24 when it becomes necessary to replace cylinders 10 and 12. It should be evident that one or more cylinders may be incorporated into the apparatus.

Since the motor 26 of valve 18 is responsive to the pressure at the downstream side of the valve by means of conduit 28 that is connected to conduit 20, the flow through valve 18 is controlled in accordance with the pressure within tank 24. When the pressure within tank 24 falls below 100 p.s.i., the pilot connected to conduit 28 is actuated to cause the valve 18 to assume the open position to thereby permit gas to flow from cylinders 10 and 12, through conduit 16, valve 18, flow line 20, valve 22, and into tank 24 to thereby raise the pressure within the tank to a value of 140 p.s.i., whereupon the pilot then actuates motor 26 which closes valve 18 to thereby stop the flow of gas from the cylinders 10 and 12. As the nitrogen gas contained within tank 24 is used, it flows through the manually operated valve 32 into the inflation line 34. The flow line 34 is preferably provided with a flexible hose and an air chuck assembly, such as generally found in most gasoline stations and garages for inflating tires. The lower extremity of the tank 24 is provided with a drain cock for removing foreign matter that may accumulate within the tank 24. The tank 24 and inflating line 34 may be the existing inflating equipment associated with a gasoline station, for example, and wherein the air compressor that is normally attached to the storage tank at valve 22 has been replaced by the illustrated manifold and high pressure cylinders that constitute all of the apparatus seen upstream of the valve 22 of FIGURE 1.

In the embodiment of FIGURE 2, the insulated liquid nitrogen vessel may be connected to the tank 64 by either of the illustrated manifolds. The first manifold is connected to the vessel 40, which in this instance is fabricated of high strength material which may be maintained at a pressure preferably in excess of 1000 p.s.i., to thereby provide a source of high pressure nitrogen gas through conduit 44 to each of the motor actuated valves 52 and 54. Valve 54 is actuated by the motor 60 in response to the upstream pressure to thereby prevent the vapor pressure of the liquid nitrogen contained within the vessel 46 from exceeding its operating or the design strength. Upon the pressure at 62 nearing the maximum operating pressure, valve 54 opens and gaseous nitrogen flows from the valve 54, through flow line 50, into the storage tank 64 where it may be used to inflate pneumatic tires and provide other useful functions through inflation flow line 79. As the gaseous nitrogen is used at flow line 70, the pressure within the tank 64 will fall to the predetermined pressure of p.s.i., whereupon the diaphragm actuated motor 56 will open valve 52 to thereby permit gaseous nitrogen to flow along the circuit or path from the vessel 40 described by flow line 44, flow line 46, valve 52, flow line 47 and 50, and into storage tank 64. In the event the gas at flow line 70 is not being utilized, the vapor pressure of the gaseous nitrogen above the liquid nitrogen contained Within the vessel 40 will continue to increase, and will eventually reach the maximum predetermined operating pressure limit, whereupon the diaphragm actuated valve 54 opens to permit gaseous nitrogen to flow into the storage tank 64 in the above described manner. Upon the pressure Within the storage tank 64 exceeding p.s.i., or the design strength of the tank 64, the safety valve 74 will be actuated by diaphragm actuated motor 78 to thereby vent or bleed off the excess pressure above 140 p.s.i. through flow line 76 and into the atmosphere. Hence the periodic flow of nitrogen from the vessel 40, which may be caused by either valve 52 or 54 opening, permits the liquid nitrogen within vessel 40 to occasionally evaporate to thereby maintain a low vapor pressure or a low boiling temperature at the surface of the liquid nitrogen.

Hence the valve 54 offers a flow path from the vessel 40 into the storage tank 64 in a manner that maintains the vapor pressure of the nitrogen within a predetermined limit, should this same result fail to be attained by the action of valve 52, which in turn is dependent upon the use of nitrogen at 70. The valve 52 is a demand valve that maintains a minimum pressure within the storage tank 64. The valve 74 is a safety valve that maintains the storage tank 64 within the maximum designed pressure limit of the vessel 64. The flow line 70 is connected to a conventional tire inflation apparatus such as a flexible hose and a conventional air chuck so as to provide the source of pressurized inert gas.

The second manifold that may be used in lieu of the above described first manifold in order to connect vessel 40 to tank 64 includes flow lines 44, 48, 49, and 50. Valve 82 may be either turned otf, or if preferred, the first manifold may be entirely removed when the use of the second manifold is deemed desirable.

Since the second manifold directly connects vessel 40 to the tank 64, the evaporation rate Within the vessel 40 is controlled by the rate of flow at 70 and/or the motor valve 74. Since the valve 74 is set to maintain the pressure within tank 64 within a predetermined mined pressure range that usually falls within the limits of 100 to 140 p.s.i., the vessel 40 and tank 64 may be fabricated from light Weight material as compared to the pressure require ments of a system carrying pressures above 1000 p.s.i.

The flow line 70, in addition to oflfering a new method of providing a tire with an insert gas, also provides a source of pressurized nitrogen that may perform all of the duties of a conventional air compressor, including the operation of air driven motors. The unit may be made into a compact package or unit that is suitable for mounting in the rear of a pick-up truck, thus eliminating the cumbersome and expensive internal combustion engine driven conventional compressor.

Having now described my invention in its broader aspects, it is not limited to the specific methods and mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

I claim:

1. A method of inflating a hollow pressurized gas filled elastomeric chamber in order to improve the durability thereof comprising passing inert gas under pressure from a high pressure storage container into a low pressure storage chamber;

controlling the flow of inert gas from the high pressure storage container into the low pressure storage chamber to provide a source of pressurized inert gas which exceeds the final pressure of the elastomeric chamber and which is less than the pressure of the high pressure storage container;

connecting a flow conduit between the elastomeric chambet and the low pressure storage chamber; inflating the elastomeric chamber with inert gas until the elastomeric chamber assumes a final pressure proportional to the pressure of the low pressure chamber;

removing the flow conduit from the elastomeric chamher.

2. The method of claim 1, and further including:

selecting the inert gas from the group comprised essentially of nitrogen, helium, carbon dioxide, carbo monoxide, and the rare gases.

3. The method of claim 1, and further including:

selecting nitrogen as the inert gas. 4. The method of claim 3, and further including: filling the high pressure storage container with suflicient liquid nitrogen to form a liquid phase and a gaseous phase within the high pressure storage container;

controlling the flow of gaseous nitrogen from the low pressure storage chamber at a rate which maintains the vapor pressure of the nitrogen within the high pressure storage container at a value below the breaking strength thereof.

5. The method of claim 1 and further including:

filling the high pressure storage container with suflicient liquid nitrogen to form a liquid phase and a gaseous phase therewithin;

controlling the flow of gaseous nitrogen from the low pressure storage chamber at a rate which maintains the vapor pressure of the nitrogen within the high pressure storage container at a value below the breaking strength thereof.

6. The method of claim 1, and further including:

selecting a pneumatic tire as the recited elastomeric chamber.

7. The method of claim 6, and further including:

filling the high pressure storage container with sufficient liquid nitrogen to form a liquid phase and a gaseous phase therewithin;

flowing gaseous nitrogen from the low pressure storage chamber at a rate which maintains the vapor pressure of the nitrogen within the high pressure storage container at a value below the breaking strength thereof.

8. The method of claim 1, and further including:

filling the high pressure storage container with suflicient liquid nitrogen to form a liquid phase and a gaseous phase therewithin;

regulating the flow of gaseous nitrogen from the high pressure container to thereby maintain the pressure therewithin below the breaking strength of the vessel; regulating the flow of gaseous nitrogen into the low pressure chamber to thereby maintain the pressure thereof at a value which exceeds the inflation pressure of the pneumatic tire;

regulating the flow of nitrogen from the low pressure chamber to the atmosphere to thereby maintain the pressure of the 'high pressure container below the breaking strength thereof.

9. The method of claim 8 and further including:

insulating the high pressure container against the transfer of heat thereinto to thereby reduce the evaporation rate of the liquid phase thereof.

10. A method of producing a source of fluid power for operating pneumatically actuated apparatus, including tools and the like, comprising the steps of:

(1) insulating a vessel containing nitrogen in both the liquid and gaseous phase;

(2) regulating the flow of gaseous nitrogen from the vessel to the atmosphere at a rate to maintain the vapor pressure of the nitrogen within the vessel at a value below the breaking strength of the vessel;

(3) flow connecting the regulated flow of gaseous nitrogen in step (2) to the pneumatically actuated apparatus to thereby provide the fluid power source for operating pneumatically actuated apparatus.

11. The method of claim 10, and further including the steps of:

(4) flow connecting the regulated flow of gaseous nitrogen from the insulated vessel to a storage chamber;

(5) maintaining the pressure of the storage chamber below its designed operating strength and above the operating pressure of the pneumatically actuated tools;

(6) carrying out step (2) by regulating the flow rate of gaseous nitrogen from the storage chamber to the atmosphere.

12. The method of claim 10, and further including the steps of:

(4) flowing the regulated flow of gases of step (2) into a storage chamber having a designed operating strength above the pressure of the regulated flow of gasses of step (2);

(5) maintaining the pressure of said storage chamber below the pressure of the vapor pressure of the container of step (1);

(6) carrying out step (2) by regulating the flow rate of gaseous nitrogen from the storage chamber.

13. The method of claim 12 wherein the storage tank in- 50 cludes the existing facilities which are normally used in conjunction with an air compressor.

References Cited UNITED STATES PATENTS 

